Massive colorless aggregate of fine acicular Quartz. Chalcedony is classified into 3 species based on optical properties:
Chalcedonite (common), Quartzine (rare), and Mogánite (Moganite) (very rare).
Each fiber of length-slow chalcedony is formed by stacked small quartz crystals parallel to the c-axis,
and that of length-fast chalcedony is by stacked small quartz crystals perpendicular to the c-axis.